1. Field of the Invention
The invention relates to a printer device with a chassis with lateral assembly plates, between which a spring-loaded, pivotable thermal print head, a transport roller for the material to be printed and the guide means therefore are disposed, which form two feed tracks, the first of which wraps around the transport roller in an approximately semicircular manner and the second wraps around the transport roller over approximately a quarter of a circle.
2. The Prior Art
A printer device of this type is known from German Patent Publication DE No. 35 09 738 A1. It has a print heat with electronically controlled print elements, which can be briefly heated and are arranged in lines which are pressed against a thermo-sensitive ink carrier, for example so-called thermal paper, which is moved vertically to the direction of the lines through the printer device. Depending on its stiffness, the thermal paper is pushed by an electronically controlled, driven transport roller, which can simultaneously be used as a printing counter support, on one of the two feed tracks by the downstream print head with the line of print elements and is subsequently guided to a discharge slot. A plurality of stationary guide elements is provided at the feed side of the transport roller, which are produced and assembled in an expensive manner from many single section elements.
Furthermore, a printer is known from German Utility Patent Publication DE-GM No. 88 03 496, which has paper guide elements with ribs extending in the direction of paper feeding and with supports, which have been produced by means of injection molding technology. However, production by means of injection molding technology is suitable, depending on the injection mold, only for guide elements for a defined printer width and requires an expensive injection mold. This printing device has two reversible supply devices for material to be printed, where in one of them a quasi endless roll is fed to the transport roller by means of an additionally driven transport device, from the back of which it runs off, and where after reversal the second feed track for individual sheets leads through the appropriately reversed paper guide elements behind the print line for further feeding to a driven draw-off device above the printer.
Furthermore, a printing device is known from European Patent Publication No. EP-A-0 288 089, where a paper feed track extends via a pair of feed rollers and a pair of draw-off rollers through a printing gap between a print head and a printing roller, the latter being touched only in the form of lines. A tear-off gap is disposed behind the pair of draw-off rollers. To make possible printing close to the upper torn-off edge, an already fed through printed roll is fed back in after being cut, so that the first printed line at the top is positioned at the print head, where, depending on the position of the first line, the top paper edge is placed in front of the pair of draw-off rollers it has left and the paper only must be grasped by the latter again after printing of a lower line, where it is possible that bunching of the printed roll and therefore inexact line printing may occur.